Line of scrimmage
WordNet
noun
(1) Line parallel to the goal lines where football linesmen line up at the start of each play in American football
"The runner was tackled at the line of scrimmage"
WiktionaryText
Noun
line of scrimmage
- Either of two imaginary lines across the football field touching one of the two apices of the football which point toward either the defensive side or the offensive side before the center is allowed to touch the ball before each play.
Usage notes
The term line of scrimmage is used for both the line on the offensive side (offensive line of scrimmage) and the one on the defensive side (defensive line of scrimmage). The zone inbetween the two lines of scrimmage is called neutral zone. The defensive line of scrimmage is used by the head linesman and his assistants to measure advancements (gains or losses) of the football along the football field.